Light source device having light-emitting diode chips of varying thickness

ABSTRACT

A light source device including a substrate, a plurality of first light emitting diode (LED) chips, and at least one second LED chip is provided. The substrate has an upper surface. The plurality of first LED chips are disposed on the upper surface and electrically connected to the substrate. Each of the first LED chips includes a first chip substrate, a first semiconductor layer, and a plurality of first electrodes, and the first electrodes are disposed on the upper surface of the substrate. The second LED chip is disposed on the upper surface and electrically connected to the substrate. The second LED chip includes a second chip substrate, a second semiconductor layer, and a plurality of second electrodes. A thickness of the second chip substrate is different from than a thickness of the first chip substrate, and the second electrodes are disposed on the upper surface of the substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation application of and claims thepriority benefit of U.S. application Ser. No. 14/886,110, filed on Oct.19, 2015, now allowed. The prior U.S. application Ser. No. 14/886,110 isa continuation application of and claims the priority benefit of U.S.application Ser. No. 14/248,343, filed on Apr. 9, 2014, now patented,issued as U.S. Pat. No. 9,165,909. The prior U.S. application Ser. No.14/248,343 claims the priority benefit of Taiwan Application Ser. No.102206511, filed on Apr. 10, 2013. The entirety of each of theabove-mentioned patent applications is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a light source module, and more particularly,to a light source module using a light-emitting diode chip as a lightsource.

Description of Related Art

Due to advantages such as long service life, small size, high shockresistance, low heat generation, and low power consumption, LEDs havebeen widely applied in indicators or light sources in householdequipment and various other equipments. In recent years, LEDs have beendeveloped to have high-power, and therefore the applications thereofhave been expanded to road illumination, large outdoor billboards,traffic lights, and similar areas. In the future, LEDs may even becomethe main illumination light source with both power-saving andenvironment-protecting functions.

In general, in an LED light source module, a plurality of LED chips isdisposed on a substrate in a matrix arrangement. However, lateral lightemitted by the LED chip is absorbed by the other adjacent LED chips. Asa result, the lateral light emitted by the LED chips cannot beeffectively utilized, thereby reducing the optical efficiency of the LEDlight source module.

SUMMARY OF THE INVENTION

The invention provides a light source module with good light-emittingefficiency.

The light source module of the invention includes a substrate, aplurality of first LED chips, and at least one second LED chip. Thesubstrate has an upper surface. The plurality of first LED chips aredisposed on the upper surface and electrically connected to thesubstrate. The second LED chip is disposed on the upper surface andelectrically connected to the substrate. A first distance is between atop surface of each of the first LED chips away from the upper surfaceof the substrate and the upper surface, a second distance is between atop surface of the second LED chip away from the upper surface of thesubstrate and the upper surface, and the second distance is greater thaneach of the first distances.

In an embodiment of the invention, the substrate includes a plurality offirst pads and a plurality of second pads. The first pads are embeddedin the upper surface of the substrate, wherein a surface of each of thefirst pads is slightly aligned with the upper surface of the substrate.Each of the first LED chips is electrically connected to the substratethrough the corresponding first pads. The second pads are disposed onthe upper surface of the substrate, wherein the second LED chip iselectrically connected to the substrate through the corresponding secondpads.

In an embodiment of the invention, each of the first LED chips includesa first chip substrate, a first semiconductor layer, and a plurality offirst electrodes. The second LED chip includes a second chip substrate,a second semiconductor layer, and a plurality of second electrodes. Thethickness of the second chip substrate is greater than the thickness ofeach of the first chip substrates, and the first electrodes and thesecond electrodes are all disposed on the upper surface of thesubstrate.

In an embodiment of the invention, the thickness of the second chipsubstrate is between a magnitude of 1 and 1+Scot(θ/2)/d″ of thethickness of each of the first chip substrates, wherein S is the spacingof each of the first LED chips and the second LED chip, d″ is thethickness of the first chip substrate, and θ is the beam angle of eachof the first LED chips.

In an embodiment of the invention, the second LED chip is locatedbetween any two adjacent first LED chips.

In an embodiment of the invention, the first LED chips surround thesecond LED chip.

In an embodiment of the invention, the first LED chips are a pluralityof flip-chip LED chips.

In an embodiment of the invention, the second LED chip is a flip-chipLED chip.

In an embodiment of the invention, the second distance is between amagnitude of 1 and 1+Scot(θ/2)/d of each of the first distances, whereinS is the spacing of each of the first LED chips and the second LED chip,d is a first distance, and θ is the beam angle of each of the first LEDchips.

In an embodiment of the invention, a side surface of the second LED chiphas a high reflectance material.

Based on the above, since in the light source module of the invention,the distance between a top surface of the second LED chip away from theupper surface of the substrate and the upper surface of the substrate isgreater than the distance between a top surface of each of the first LEDchips away from the upper surface of the substrate and the upper surfaceof the substrate, the second LED chip can effectively reflect laterallight emitted from the first LED chips such that the light source modulehas good light-emitting efficiency.

Several exemplary embodiments accompanied with figures are described indetail below to further describe the invention in details.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 illustrates a cross-sectional schematic view of a light sourcemodule of an embodiment of the invention.

FIG. 2 illustrates a cross-sectional schematic view of a light sourcemodule of another embodiment of the invention.

FIG. 3 illustrates a schematic top view of a light source module of yetanother embodiment of the invention.

FIG. 4 illustrates a schematic top view of a light source module ofstill yet another embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1 illustrates a cross-sectional schematic view of a light sourcemodule of an embodiment of the invention. Referring to FIG. 1, a lightsource module 100 includes a substrate 120, a plurality of firstlight-emitting diode (LED) chips 140, and at least one second LED chip160 (only one is schematically shown in FIG. 1). The substrate 120 hasan upper surface 120 a. The plurality of first LED chips 140 aredisposed on the upper surface 120 a and electrically connected to thesubstrate 120. The second LED chip 160 is disposed on the upper surface120 a and electrically connected to the substrate 120. A first distanced1 is between a top surface 140 a of each of the first LED chips 140away from the upper surface 120 a of the substrate 120 and the uppersurface 120 a of the substrate 120, a second distance d2 is between atop surface 160 a of the second LED chip 160 away from the upper surface120 a of the substrate 120 and the upper surface 120 a of the substrate120, and the second distance d2 is greater than each of the firstdistances d1. In this way, the second LED chip 160 can effectivelyreflect lateral light emitted from the first LED chips 140.

Referring further to FIG. 1, specifically, the substrate 120 includes aplurality of first pads 124 and a plurality of second pads 126. Thefirst pads 124 are embedded in the upper surface 120 a of the substrate120, wherein a surface 124 a of each of the first pads 124 is slightlyaligned with the upper surface 120 a of the substrate 120, and each ofthe first LED chips 140 is electrically connected to the substrate 120through the corresponding first pads 124. The second pads 126 aredisposed on the upper surface 120 a of the substrate 120, wherein thesecond LED chip 160 is electrically connected to the substrate 120through the second pads 126. In the present embodiment, the first pads124 can be regarded as embedded pads, and the second pads 126 can beregarded as ordinary pads. That is, a height difference H is between thefirst pads 124 and the second pads 126. The design of each of the firstpads 124 and the second pads 126 allows the second distance d2 betweenthe top surface 160 a of the second LED chip 160 and the upper surface120 a of the substrate 120 to be greater than the first distance d1between the top surface 140 a of each of the first LED chips 140 and theupper surface 120 a of the substrate 120. Preferably, the seconddistance d2 is between a magnitude of 1 and 1+Scot(θ/2)/d1 of each ofthe first distances d1, wherein S is the spacing of each of the firstLED chips 140 and the second LED chip 160, d1 is the first distance, andθ is the beam angle of each of the first LED chips 140.

Moreover, in the present embodiment, the first LED chips 140 and thesecond LED chip 160 can be the exact same LED chips. That is, the firstLED chips 140 and the second LED chip 160 can have, for instance, thesame dimension and size and emit light of the same color. Therefore, thesecond distance d2 of the present embodiment being greater than each ofthe first distances d1 is the result of the structural configuration ofeach of the first pads 124 and the second pads 126 of the substrate 120.Of course, the invention does not limit the structural pattern of eachof the first LED chips 140 and the second LED chip 160. In otherembodiments, the first LED chips 140 and the second LED chip 160 can beLED chips of different dimensions, different sizes, and emit light ofdifferent colors. The different LED chips still belong to the technicalsolution applicable to the invention and do not depart from the scope ofthe invention to be protected. Moreover, the substrate 120 of thepresent embodiment can be a transparent substrate such as a sapphiresubstrate. The first LED chips 140 can be a plurality of flip-chip LEDchips. The second LED chip 160 can be a flip-chip LED chip.

Since a height difference H is between the first pads 124 and the secondpads 126 of the substrate 120, when the first LED chips 140 and thesecond LED chip 160 have the same dimension and size, the seconddistance d2 between the top surface 160 a of the second LED chip 160away from the upper surface 120 a of the substrate 120 and the uppersurface 120 a of the substrate 120 is greater than the first distance d1between the top surface 140 a of each of the first LED chips 140 awayfrom the upper surface 120 a of the substrate 120 and the upper surface120 a of the substrate 120. In this way, the second LED chip 160 caneffectively reflect lateral light emitted from the first LED chips 140such that the light source module 100 has good light-emittingefficiency.

It should be mentioned here that, the following embodiments use thereference numerals of the embodiments above and a portion of thecontents thereof, wherein the same numerals are used to represent thesame or similar elements and descriptions of the same technical contentsare omitted. The omitted portions are described in the embodimentsabove, and are not repeated in the embodiments below.

FIG. 2 illustrates a cross-sectional schematic view of a light sourcemodule of another embodiment of the invention. Referring to FIG. 2, alight source module 200 of the present embodiment is similar to thelight source module 100 of FIG. 1, with the difference being: aplurality of first LED chips 240 and a second LED chip 260 of thepresent embodiment have different structural patterns.

Specifically, each of the first LED chips 240 of the present embodimentincludes a first chip substrate 242, a first semiconductor layer 244,and a plurality of first electrodes 246. The first semiconductor layer244 is formed by a first-type doped semiconductor layer 244 a, asecond-type doped semiconductor layer 244 b, and a first light-emittinglayer 244 c, wherein the first light-emitting layer 244 c is between thefirst-type doped semiconductor layer 244 a and the second-type dopedsemiconductor layer 244 b. The second LED chip 260 includes a secondchip substrate 262, a second semiconductor layer 264, and a plurality ofsecond electrodes 266. The second semiconductor layer 264 is formed by athird-type doped semiconductor layer 264 a, a fourth-type dopedsemiconductor layer 264 b, and a second light-emitting layer 264 c,wherein the second light-emitting layer 264 c is disposed between thethird-type doped semiconductor layer 264 a and the fourth-type dopedsemiconductor layer 264 b. As shown in FIG. 2, the thickness d′ of thesecond chip substrate 262 is greater than the thickness d″ of each ofthe first chip substrates 242, and the first electrodes 246 and thesecond electrodes 266 are all disposed on the upper surface 220 a of thesubstrate 220. In other words, in the present embodiment, the thicknessd″ of the first chip substrate 242 is different from the thickness d′ ofthe second chip substrate 262, and therefore a second distance d2′ isgreater than a first distance d1′. Preferably, the thickness d′ of thesecond chip substrate 262 is between a magnitude of 1 and 1+Scot(θ/2)/d″of the thickness d″ of each of the first chip substrates 242, wherein Sis the spacing of each of the first LED chips 240 and the second LEDchip 260, d″ is the thickness of the first chip substrate 242, and θ isthe beam angle of each of the first LED chips 240.

Since in the present embodiment, the thickness d″ of the first chipsubstrate 242 of the first LED chips 240 is different from the thicknessd′ of the second LED chip substrate 262 of the second LED chip 260, thesecond distance d2′ between the top surface 260 a of the second LED chip260 away from the upper surface 220 a of the substrate 220 and the uppersurface 220 a of the substrate 220 is greater than the first distanced1′ between the top surface 240 a of each of the first LED chips 240away from the upper surface 220 a of the substrate 220 and the uppersurface 220 a of the substrate 220. In this way, the second LED chip 260can effectively reflect lateral light emitted from the first LED chips240 such that the light source module 200 has good light-emittingefficiency.

FIG. 3 illustrates a schematic top view of a light source module of yetanother embodiment of the invention. Referring to FIG. 3, a plurality offirst LED chips 340 and a plurality of second LED chips 360 of a lightsource module 300 are arranged in a matrix on a substrate 320. To makethe second LED chip 360 reflect lateral light emitted from the first LEDchips 340 effectively, each of the second LED chips 360 is locatedbetween any two adjacent first LED chips 340. As shown in FIG. 3, theperiphery of each of the first LED chips 340 has at least four secondLED chips 360. As a result, lateral light of the first LED chips 340 canbe effectively reflected such that the light source module 300 hasbetter light-emitting efficiency.

FIG. 4 illustrates a schematic top view of a light source module ofstill yet another embodiment of the invention. Referring to FIG. 4, inthe present embodiment, a plurality of first LED chips 440 of a lightsource module 400 surround a second LED chip 460. In this way, thesecond LED chip 460 located in the center can effectively reflectlateral light emitted from the first LED chips 440 in the periphery.Alternatively, in other embodiments not shown, the plurality of firstLED chips of the light source module can be arranged to form a pluralityof ring structures, the plurality of second LED chips can be arranged toform a plurality of ring structures, and the ring structures can becoaxially arranged. In particular, the ring structures formed by thefirst LED chips and the ring structures formed by the second LED chipsare alternately arranged. Such configuration still belongs to thetechnical solution applicable to the invention and does not depart fromthe scope of the invention to be protected. In this way, the second LEDchip 460 can also effectively reflect lateral light emitted from thefirst LED chips 440 such that the light source module 400 has betterlight-emitting efficiency.

Based on the above, in the light source module of the invention, thedistance between the top surface of the second LED chip away from theupper surface of the substrate and the upper surface of the substrate isgreater than the distance between a top surface of each of the first LEDchips away from the upper surface of the substrate and the upper surfaceof the substrate so as to achieve the effect of the second LED chipreflecting lateral light emitted from the first LED chips effectively.As a result, the light source module has good light-emitting efficiency.

Moreover, if the effect of the second LED chip reflecting lateral lightemitted from the first LED chips is to be increased, then a side surfaceof the second LED chip has a high reflectance substance (not shown). Inthis way, not only the absorption of lateral light of the first LEDchips can be reduced such that lateral light of the first LED chips iseffectively emitted outward after being reflected, lateral light of thesecond LED itself can also be reflected such that lateral light of thesecond LED is emitted upward in a more concentrated manner.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of thedisclosed embodiments without departing from the scope or spirit of theinvention. In view of the foregoing, it is intended that the disclosurecover modifications and variations of this specification provided theyfall within the scope of the following claims and their equivalents.

What is claimed is:
 1. A light source device, comprising: a substratehaving an upper surface; at least one first light-emitting diode (LED)chip disposed on the upper surface and electrically connected to thesubstrate; and at least one second LED chip disposed on the uppersurface and electrically connected to the substrate, wherein a firstdistance from the upper surface to a top surface of the at least onefirst LED chip is higher than a second distance from the upper surfaceto a top surface of the at least one second LED chip, and a thickness ofthe at least one second LED chip is different from a thickness of the atleast one first LED chip, wherein the at least one first LED chipcomprises a first chip substrate, the at least one second LED chipcomprises a second chip substrate, and a thickness of the second chipsubstrate is different from a thickness of the first chip substrate. 2.The light source device as recited in claim 1, wherein the at least onefirst LED chip or the at least one second LED chip is flipped on thesubstrate.
 3. The light source device as recited in claim 1, wherein theat least one first LED chip and the at least one second LED chip emitlight of a same color.
 4. The light source device as recited in claim 1,wherein the at least one first LED chip and the at least one second LEDchip have a same dimension in horizon.
 5. The light source device asrecited in claim 1, wherein when a quantity of the at least one firstLED chip or a quantity of the at least one second LED chip is plural,the at least one first LED chip(s) and the at least one second LEDchip(s) are arranged alternately.